VOCABULARY COMPETENCE IN EARLY-CHILDHOOD - MEASUREMENT, LATENT CONSTRUCT, AND PREDICTIVE-VALIDITY

Mr, systematically examined relations among 6 measures of child langua ge derived from 3 sources, including observations of the child's speec h with mother, experimenter assessments, and maternal reports. A total of 184 20-month-olds and their mothers contributed complete informati on about child language comprehension and expression Correlations of c hild language measures with socioeconomic status and maternal educatio n were accounted for, as were correlations of child language measures with mothers' verbal intelligence, maternal report measures with mothe rs' tendency to respond in a socially desirable fashion, and experimen ter assessments with child social competence. Structural equation mode ling supported (1) strong relations among child language measures deri ved from observations of the child's speech with mother, experimenter assessments, and maternal reports; (2) the loading of multiple measure s of child language from different sources on a single latent construc t of vocabulary competence; and (3) the predictive validity of the voc abulary competence latent variable at 20 months, as well as receptive vocabulary specifically, for both verbal and performance IQ (verbal be tter than performance) at 48 months. Neither an index of child monolog ing (a nonvocabulary language measure) nor symbolic play (a nonlinguis tic representational measure) covaried with vocabulary competence. Gir ls consistently outperformed boys on individual language measures, but no differences emerged in any model in the fit for boys and girls.